PLMN selection in 5G NR

5G NR
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1

Hello Experts,

How does UE do PLMN selection in 5G/NR?
Is it the same as 4G?

How does it choose Operator?

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Thanks

2

  1. The UE shall scan all RF channels in the NR bands according to its capabilities to find available PLMNs.

  2. On each carrier, the UE shall search for the strongest cell and read its system information, in order to find out which PLMN(s).

  3. If the UE can read one or several PLMN identities in the strongest cell, each found PLMN shall be reported to the NAS as a high-quality PLMN (but without the RSRP value), provided that the following high-quality criterion is fulfilled.

  4. The search for PLMNs may be stopped on request from the NAS.

  5. The UE may optimise PLMN search by using stored information e.g. frequencies and optionally also information on cell parameters from previously received measurement control information elements

  6. Once the UE has selected a PLMN, the cell selection procedure shall be performed in order to select a suitable cell of that PLMN to camp on.

The UE select (decides) for a particular PLMN after reading SIB1 and getting PLMN information.

In SIB 1 UE read PLMN information for each available MNO like EE, O2, Vodafone or Three (i.e. for UK).

This information can be found in plmn-IndentityList : MCC and MNC

3

Almost the same, it still follows the same 23.122 procedure. Only difference might be PLMNwact , RAT priority in SIM card with an extra entry for 5G.

1 Like
4

Hi, anybody can comment out that clause at 23.122 4.4.3 (rel15)

PLMN selection: “If an entry indicates more than one access technology” meaning

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Does that mean we have set different RATS for same PLMN, then no priority order is applied from SIM?

5

HPLMN is a prioritized list of PLMN/Access Tech items

So with this list:

  • PLMN X, 2G+3G
  • PLMN Y, 4G

There is no priority between 2G and 3G on PLMN X - but 4G on PLMN Y will have lower priority.

6

Thanks for comment!

We have only 1 entry for all RATs under same PLMN, so the all RATs should have same priority then.

7

Agreed!

8

I have changed 1st plmn as NGRAN and 2nd others.

Phone directly goes to SA :slight_smile:

Just wondering when SA is not available, whether UE will have some delay to camp on LTE pLMN.

Any comments?

Also at LTE option there is rel 13&above and rel14&above options when selecting plmn order, anybodu knows what it is actually?

Seems to me rel13 and 14 is quite old.

10

Hi Guys.

If we return to that discussion…

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What happens if we put 1st priority as NR_SA PLMN and 2nd PLMN (same PLMN) for rest of the RAT.

For smartphones in an area where no SA coverage, cell selection to LTE will be delayed?

What is your opinion?